presented bypresented by

Burrell ScarlettBurrell ScarlettEVERGROW HORTICULTURAL PRODUCTSEVERGROW HORTICULTURAL PRODUCTS

IntroductionEradication of hunger and food

security for all is an objective of governments around the world.

Water, fertilizers and food security are intimately connected in irrigated agriculture.

Food requirements will continue to increase as world population grows, while global water and fertilizer resources are limited.

Introduction To make the best use of water and

fertilizers for irrigated agriculture and to improve their efficiency, strategies must be developed and implemented to this end.

This presentation seeks to review the relationship between Irrigation Water Quality and Fertilizer Formulation and Efficacy.

World Fertilizer Consumption From the 1950’s to the present, the world

consumption of fertilizers continues to increase, exceeding some 160 million tons in 2013.

  

Fertilizer Use Efficiency

Law of the Minimum…. states that the yield of any

crop depends on the most limited factor in the growing cycle

Fertilizer Use EfficiencyPlant roots will not absorb fertilizers efficiently if the pH

range is not optimized i.e. irrigation water pH affects the

availability of all mineral nutrients. Figure 2 below shows that

the absorption of all essential nutrient elements is optimized at

pH 5.5 - 6.5.

The feeding of specific elements as supplements should be

done within their specified range as indicated below. Example,

Molybdenum is best applied within an alkaline solution of pH

greater than 7, whereas Manganese is best applied in an acidic

solution of pH less than 5.5.

Figure 2: Influence of nutrients uptake by pH

Of the 3 major nutrients required by plants, Phosphorus is the one most affected by fluctuation in media pH. Fe and Al phosphates ppt – acidic pH media Ca and Mg phosphates ppt – basic pH media

Fig 3

CORRECTING THE MEDIA pH

•Water conditioners•Compost/manures

•Lime•Specialized fertilizers

CORRECTING THE MEDIA pH

For Proper Nutrient For Proper Nutrient Uptake,Uptake,

The Goal Is To The Goal Is To Achieve A Stable Achieve A Stable

Media pH Over TimeMedia pH Over Time

Sample ASample A Sample BSample B

pH = 9pH = 9 pH = 7pH = 7

One drop of acid to get pH 6One drop of acid to get pH 6 Ten drops of acid to get pH 6Ten drops of acid to get pH 6

The Effect of Water Alkalinity on Media The Effect of Water Alkalinity on Media pH and Acid RequirementpH and Acid Requirement

Little or no effect on the Little or no effect on the growing medium pHgrowing medium pH

Increases growing medium Increases growing medium pHpH

Alk = 50 Alk = 50 ppmppm Alk = 300 Alk = 300 ppmppm

CaMg(COCaMg(CO33))22

Dolomitic Dolomitic

limestonelimestone

CaCa2+2+ + Mg + Mg2+2+ + 2CO + 2CO332-2-

HardnessHardness

AlkalinityAlkalinity

Hardness and Alkalinity Generally Hardness and Alkalinity Generally Go Hand-In-Hand but They Are Go Hand-In-Hand but They Are

NOT One and the SameNOT One and the Same

You Can Use the Water Hardness You Can Use the Water Hardness to Estimate Its Alkalinityto Estimate Its Alkalinity

Calcium and magnesium are the major Calcium and magnesium are the major contributorscontributors

“ “hard water” has a high Ca and/or Mghard water” has a high Ca and/or Mg “ “hard water” is hard water” is generallygenerally associated associated with high alkalinitywith high alkalinity can have hard water and low can have hard water and low alkalinity – water high in CaClalkalinity – water high in CaCl2 2 and/orand/or

MgClMgCl22

HardnessHardness

FertilizersFertilizers and and WaterWater

It is Alkalinity, not media It is Alkalinity, not media / soil pH that determines / soil pH that determines

a stable pH over time.a stable pH over time.

5

6

7

8

9

0 4 8 12 16

Well (320 ppmalkalinity)Acidified well (120ppm alkalinity)Well +RO Blend (130ppm alkalinity)RO purified (<20 ppmalkalinity)

Weeks from PlantingWeeks from Planting

Roo

t Med

ia p

HR

oot M

edia

pH

The same fertilizer 97% The same fertilizer 97% nitrate nitrogen at 200 nitrate nitrogen at 200

ppm N was appliedppm N was applied

(adopted from (adopted from Greenhouse GrowerGreenhouse Grower, , January 2001, p.72)January 2001, p.72)Effect of Water Alkalinity on Media pH Effect of Water Alkalinity on Media pH

Over TimeOver Time

9 

8

 7

 6

 5

0 4 8 12 16

Nutrients Tomato* Pepper 1* Lettuce General Crops

NO3-N 175 265 218 195

NH4-N 25 25 28 25

Total N 200 290 246 220

P 80 180 62 50

K 300 400 240 312

Ca 250 300 190 180

Mg 70 44 50 45

S 90 32 70 48

ELEMENTS ppm ppm ppm ppm

B 0.7 0.7 0.7 0.7

Fe 3.6 3.6 4.2 3.6

Mn 2.2 2.2 2.2 2.2

Zn 0.23 0.23 0.23 0.23

Cu 0.07 0.07 0.07 0.07

Mo 0.05 0.05 0.05 0.05

The Plant Needs

IRRIGATION WATER AND ITS NUTRIENTS

Irrigation Water contains elements or compounds that are essential for plant growth, such as nitrate, phosphate, potassium, sulfate, calcium, magnesium, iron, zinc, copper and manganese.

Very often these elements are sufficient to sustain plant growth for the entire cropping season.

Proper crop nutrient management often compensates for these nutrients in the irrigation water.

Most producers do not consider irrigation water nutrient concentrations when developing a fertilizer program or recipes. This overlooked source of plant nutrients is important and can save producers money and prevent adding of unused quantities of nutrients to the agri-ecosystem.

MSU WELL WATER (ppm) pH 7.9Calcium = 104 Magnesium = 34 Sodium = 8.5 Potassium = 1.4 Iron = 0.84 Manganese = 0.04 Copper = 0.70 Zinc = 0.17 Sulfate (as SO4) = 91Bicarbonate = 383

   Well Water Special  RO Water Special

   (19-4-23)  (13-3-15) Nitrate Nitrogen  13.6%  12.5% Ammoniacal Nitrogen  5.7%  0.5% Urea Nitrogen  0.0%  0.0% Phosphorus as P2O5  4.0%  3.0% Potassium as K2O  23.0% 15.00% Calcium  2.0%  8.0% Magnesium  0.0%  2.0% Iron  0.16%  0.17% Manganese  0.08%  0.08% Zinc  0.08%  0.04% Copper  0.08%  0.04% Boron  0.01%  0.01% Molybdenum  0.01%  0.01%

MSU FERTILIZER RECIPES FOR WELL

& R O / RAIN WATER

TESTING pH & ECThe 2:1 method *Step 1. Collect small amounts of substrate as per prescribed media sampling techniques. Thoroughly mix the samples to ensure uniformity. *Step 2. Measure a known volume of substrate in a beaker or cup [usually 2-4 oz. (50 to 100 ml)]. The container should be firmly filled with the substrate so that it is slightly compressed. Place 2 equal volume of distilled water into container and mix thoroughly. Allow the slurry to stand for 30-60 minutes before measuring pH and EC.

EC (mS/cm) SUBSTRATE

0 – 0.25 No fertility

0.30 to 0.75 Low fertility

0.30 to 1.50 Acceptable range

0.75 to 2.00 High fertility

>2.50 Potential root damage

TESTING pH & ECStep 3. Measure pH and EC directly in the slurry. Acceptable media pH levels for whichever method used: 5.5 – 6.5Acceptable levels for media fertility may vary as shown below.

Modern ProductionGrowers

should NOT have

nutritional problems

Water Alkalinity, not soil pH that influence nutrient availability over the long term.

THE END